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@ntrntsts stent ffies NELSON BARNUM AND GEORGE o. SGHEEIEEE, 0E sT, Lousnissousi,

Asslelvons To NELSON Bannon, or THE SAME PLACE. i

Letters Patent No. 65,991, dated June 25, 1867.`

MPROVEMENTS Ili DBELlNGrINSTRUMENTS.

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TO ALL WHOM I'l MAY CONCERN:

Y Be it known that we, NELSON BARNUM and GEORGE C. SCHREIBER, have invented a new and useful Drilling- Instrument for watchmakers use and other like purposes; and we do hereby declare that the following is a. full and clear description thereof, reference being had to the accompanying drawings, n.nd to the letters of reference marked thereon.

The nature of this invention consists in constructing the drill and driilstock vin such a manner as to make the drill or tool set in the stock eccentrically, and also to make this eccentricity adjustable, by means of a -setscrew, so that diameter of theputh described by the tool may be made of any required size, simply by turning the set-screw in or out.

To enable those skilled in the art 'to make and useour improvedV drilling-instrument, we will proceed to describe its construction and operation. i

Figure 1 is a sectional elevation of the improved instrument, and the socket in which it works.

Figure 2 is a plan of the gauge used for setting it.

Figure 3 is an elevation of the pin used for centring the socket on the gauge previous to the insertion of. the drill-stock.

Figure 4 is an elevation of the drill-stock. 4 i s Figure 5 is an enlarged view, showing the'tool and its adjusting-spring, also vthe set-screw used for adjusting the eceentricity of the tool. I

Figure 6 is one of' the tools or bits shown in elevation.

A is the socket in which the drill-stock B revolves. On the lower e'nd of `1t there is a shelf vor ilange, a,

which is used for securing it to the lathe or adjusting it on the gauge, as will be hereinafter more fully described. A portion of the lower ond of the socket should be left open, so as to disclose the tool, for the purposes of adjustment. A nut or screw-head, A, is screwed on to the top end or head ofthe socket A, and may be screwed up or down, for the purpose of regulating the depth to which the tool is intended to out. A loose collar, B', on the top end ofthe drill-stock B, may be used for the same purpose. A smallset-screw, b, may be used to set the collar fast at any desired position. The stock B is fitted into the socket A, so that it may turn easily therein, and it is provided with a pulley, 61, on its upper end for the purpose of transmitting motion to it. All of the foregoing parts of this instrument are similar to machinery of the kind now in use, and hence are not vclaimed as our invention. A cylindrical cavity is bored in the bottom end1 of the. drill-'stock B of sudicient depth and area to'receivc the spring C, to the lower end of which the drill or other tool, c, is attached. An enlarged head, c, at the upper endpof the spring, just lls the cavity bored in. B to receive it, and holds that end of the spring in a. fixed position. The spring is set so as to draw to one side of the orifice at the bottoni of B, and near 'its lower end it is perforated for the screw c2, and the female threads for the said screw are cut in the said spring. There are tapering slots in the sides of the drill-stock at its lower end, for the reception of the ends of the screw e2, as clearly shown in fig. 4. These slots and the two ends of the screw are so nicely adjusted to each other that when the spring is shoved into its place in the stock, the ends of the screw fit tightly to the said stock, and prevent the spring from slipping out. A collar shown on the head of the screw slips inside of the cavity of the stock, and rests against the same, so as to enable the screw to be turned, and thereby force the spring off from or let it up to one side, as may he recluired to set the tool c in the required position. By means of the screw e2 the tool e may be set to travel in a larger or smaller circle, just es'may be required, and a smaller or larger hole may thus he bored with the same hit by merely changing theY adjustment. By having a slot cut up into the tool from its lower end, a ridge mayl he formed around a hole that is bored by this instrument suitable for the setting of a jewel in a watchplate. y Then, by inserting a bnrnishing-instrument in place ol' the tool c, the setting of a jewel may be completed. The tool c, suitable for forming the ridge above referred to, is shown in fig. 6.' When this instrument is to be set to any1 required sized hole, the stock B is to be withdrawn from the socket A, and the foot a set on the gauge D. The pin E will then he inserted in the stock, and its cone-pointed end plocedrin the desired cavity of the gauge, so as to ,properly centre the socket. The pin will then be removed from the socket7 and thestock B inserted init-s place, when the tool c maybe set so as to bore out the hole ineated on the gauge.

Having iescribed our invent-ion, what we claim, s-

1. The stock B, with a tod-cavity and apering slots for the screw ol in its lower end, combined with the s ,ring `O ami the set-screw c2, substantiay as described and .set forth.

The slotted tool c, iii combination with the spring-holder C and its set-screw c2, and fhe tool-stock B, when acting substantially as set forth.

NELSON BARNUM, GEORGE C. SCHREIBER. Witnesses z M. RANDOLPH,

S. M. RANDOLPH. 

